Esters of the 4-piperidinol systems have been synthesized for pharmacological and biochemical study. Two CNS classes have been found: (1) non-addicting analgesics (mice, rhesus monkeys); (2) antiepileptics (mice). The analgesic receptor is being studies using bovine brain homogenates. Arecolone methiodide is a very potent nicotinic agonist in the rectus abdominus muscle assay. Substituted pyrrole carboxylic acids have shown antiinflammatory activity (carageenin-induced edema in rats). Quantitative structure-activity relationships have been made.